hi i brought an f4i in the begining of the summer it ran really good. i put a 57 tooth sprocket on it and it felt pretty torky, mind you i rode a 900rr with a -2 +10 set up. but lattely the bike feels like it bogs, for instance cant do nothing till the bike runs for a few minutes, if i open up the throttle it almost shuts off. but then after it worms up it still feels like it bogs while giving it gas but not to the point of shutting of but to the point of losing some low end. any ideas?

 

Hey this may help...oviously u know that a motor needs 3 elements...Air-Fuel-Spark-and for arguments sake timed combustion...anyway u said the bike runs, but shitty at bottom end...try the easy stuff first...spark plugs..burt up wire or coil would effect the bikes spark causin it to maybe have a small miss in it...maybe ur outta time, f4i are known for that, but a easy fix with a new tensioner...what kinda pipe do u have on there? stock or aftermarket..u may just have to get the bike maped to match a aftermarket pipe due to the change in performance? i know some 929's to be very boggy down in the low rpms..but after 3g it clears up...so try the easy stuff first..hope that helps..jus my

 

it's the plugs....90% of the time

 

we were out stuntin tonight and my boys f4i started to run sluggish the bottom air house on the airbox the little one closest to the rear on the bottom,, it came off that will make it run like crap

 

first thing in the am going to try all that was mentioned as for the pipe i stock pipe cut down i was thinking that might have something to do with bing that when it was cut down there were 4 holes in there and the cap rest about little less then 1/4 inch from the holes. never saw a pipe look like that on the inside.

 

My old F2 had the same problems it was the plugs

 

I first dumped fuel injector cleaner in and it worked temporarily but then tried the following.

Heres are a few:

Plugs, get the iridiums.
Check all hoses.
Fuel filter. (Last resort)
Fuel pump (Last resort)
Clogged fuel rail

The Tri-fixer
TB) Fuel pressure regulator.
TB) Injectors.
TB) Throttle Body Boots loose.

Just swapping out with a new TB (Throttle Body) cured my bike and its golden now.